When an image is captured by a camera, the image does not represent a single instant of time but it represents the scene over a period of time. So any object moving with respect to the camera after the convolution with PSF (point spread function), e.g. box filter or broadband filter, the image will be blurred. Motion blur can happen due to unsteady hand movement or object motion while capturing the image and the image will be smeared along the direction of relative motion.
Motion blur can be handled in three different ways                1. Short Exposure Time Imaging        2. Image Deblurring using Conventional Camera Approach        3. Image Deblurring using Flutter Shutter Approach        
In the case of short exposure time imaging each individual frame can be noisy. The lower the exposure time, the lower the number of photons that reach the sensor, hence the captured image is noisier. The color tone is also lost since not enough light is captured by the sensor.
In the case of the second above-mentioned deblurring approach using conventional camera, high spatial frequencies are lost because of the box-shaped nature of the camera exposure pattern as shown in FIG. 1. In FIG. 1 a diagram is shown having the time on the x-axis and the indication of opening and closing the shutter on the y-axis.
When an image convolves with such kind of response it smears the high frequencies contents.
So in case of a band limited response, the PSF coverage of the Fourier domain is incomplete and information is lost. Therefore a flat blur and motion blurring occurs resulting in a continuous smear. This is explained in more detail with reference to FIG. 2. FIG. 2 shows the Fourier spectrum of a PSF. In the x-axis the normalized frequency is shown and on the y-axis the magnitude in dB. As can be seen, the Fourier spectrum contains several zeros indicated with 30 in its spectrum. In that case the Fourier spectrum of PSF contains zeros in its spectrum as shown in FIG. 2, the inverse filtering will amplify noise and produce ringing artifacts and make the deconvolution an ill-posed problem.
Now the third above-mentioned possibility of deblurring using the flutter shutter approach will be explained. Such an approach is described in document R. Raskar et al. “Coded Exposure Photography: Motion Deblurring using Fluttered Shutter”, which is incorporated herein by reference. The shutter is opening and closing over a single exposure time according to a random binary coded sequence as for example described in document A. Agrawal et al. “Coded Exposure Deblurring: Optimized Codes for PSF Estimation and Invertibility”. The sequence is chosen so that the resulting motion blur PSF has a flat frequency spectrum and high spatial frequencies are preserved. A block diagram of this system is shown in FIG. 3.
The system 100 comprises a coded exposure camera 101, which takes several frames using the flutter shutter approach. The blurred image 111 is then submitted to a PSF estimation unit 103. Information 120 received by user interaction is also submitted to the PSF estimation unit 103, which determined the PSF. This information 113 is then submitted to the deconvolution unit 105, which carries out deconvolution and the final deblurred image 115 is output.